The Jaramillo reversal was a reversal and

excursion An excursion is a trip by a group of people, usually made for leisure, education, or physical purposes. It is often an adjunct to a longer journey or visit to a place, sometimes for other (typically work-related) purposes. Public transportation ...

of the

Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magneti ...

that occurred approximately one million years ago. In the geological time scale it was a "short-term" positive reversal in the then-dominant Matuyama reversed magnetic chronozone; its beginning is widely dated to 990,000 years before the present ( BP), and its end to 950,000 BP (though an alternative date of 1.07 million years ago to 990,000 is also found in the scientific literature). The causes and mechanisms of short-term reversals and excursions like the Jaramillo, as well as the major field reversals like the

Brunhes–Matuyama reversal The Brunhes–Matuyama reversal, named after Bernard Brunhes and Motonori Matuyama, was a geologic event, approximately 781,000 years ago, when the Earth's magnetic field last underwent reversal. Estimations vary as to the abruptness of the rever ...

, are subjects of study and dispute among researchers. One theory associates the Jaramillo with the Bosumtwi impact event, as evidenced by a

tektite Tektites (from grc, τηκτός , meaning 'molten') are gravel-sized bodies composed of black, green, brown or grey natural glass formed from terrestrial debris ejected during meteorite impacts. The term was coined by Austrian geologist Fra ...

strewnfield The term strewn field indicates the area where meteorites from a single fall are dispersed. It is also often used for the area containing tektites produced by large meteorite impact.''Tektites in the geological record: showers of glass from the sk ...

in the

Ivory Coast Ivory Coast, also known as Côte d'Ivoire, officially the Republic of Côte d'Ivoire, is a country on the southern coast of West Africa. Its capital is Yamoussoukro, in the centre of the country, while its largest city and economic centre is ...

, though this hypothesis has been claimed as "highly speculative" and "refuted". Courtillot, Vincent. ''Evolutionary Catastrophes: The Science of Mass Extinction.'' Cambridge, Cambridge University Press, 1999; p. 104. A later study found the deposition of the Ivory Coast strewn field and the onset of the Jaramillo reversal not to be contemporaneous as previsouly inferred. They are separated in time by 30,000 years.Schneider, D.A. and Kent, D.V., 1990. ''Ivory Coast microtektites and geomagnetic reversals''. ''Geophysical Research Letters'', 17(2), pp.163-166.

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* Earth Pleistocene events Geomagnetic reversal {{Geology-stub

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